Tip-enhanced Raman spectroscopy resolved "resonance" Raman scattering with 1-nm resolution in ultrathin zinc oxide films epitaxially grown on a single-crystal silver surface. Tip-enhanced "resonance" Raman scattering can be used to investigate a specific chemical structure at nanoscale and even at the single-molecule level and also provides a new approach for the atomic-scale optical characterization of local electronic states. This will be a powerful tool to study, for instance, local defects in low-dimensional materials and active sites of heterogeneous catalysis.

A research team at Fritz-Haber Institute in Berlin, headed by Dr. Takashi Kumagai, demonstrated tip-enhanced "resonance" Raman spectroscopy. Resonance Raman spectroscopy is a powerful tool to analyze a specific chemical structure at a high sensitivity, but its spatial resolution has been restricted to be a few hundred nm due to the diffraction limit. Extreme field confinement at a metal tip apex through localized surface plasmon excitation allows to break this limitation and now attain 1-nm resolution. Tip-enhanced Raman spectroscopy takes advantage of atomic resolution imaging of scanning probe microscopy and enhanced Raman scattering through localized surface plasmon excitation. The research team revealed tip-enhanced resonance Raman scattering in which both physical and chemical enhancement mechanisms are operative. The underlying process was examined by modifying the localized surface plasmon resonance in the scanning tunneling microscope junction and by recording different-thickness zinc oxide films that exhibit a slightly different electronic structure. In addition, the correlation between tip-enhanced resonance Raman scattering and local electronic states is resolved in combination with scanning tunneling spectroscopy that maps the local electronic state of the zinc oxide film. Our results explicitly show that a confined electromagnetic field can interact with local electronic resonances at the (sub)nanometer scale.

Fig. 3 Correlation between tip-enhanced Raman scattering and the local electronic structure of the ZnO film. (a-b) STM image and STS mapping of the ZnO film. (c) Tip-enhanced Raman spectra recorded at different sites over the ZnO film (red and blue) and the Ag surface (black). (d) Constant-current STS recorded at different sites over the ZnO film. (e-g) Line profile of STM height, STS intensity, and Raman intensity. The line is indicated in (a-b). (h) Tip-enhanced resonance Raman spectra recorded along the line in (a-b). Credit: Takashi Kumagai

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

E-mail the story

'Resonance' raman spectroscopy with 1-nanometer resolution

Note

Your email address is used only to let the recipient know who sent the email. Neither your address nor the recipient's address will be used for any other purpose.
The information you enter will appear in your e-mail message and is not retained by Phys.org in any form.

Your message

Newsletter sign up

Get weekly and/or daily updates delivered to your inbox.
You can unsubscribe at any time and we'll never share your details to third parties.

Your Privacy

This site uses cookies to assist with navigation, analyse your use of our services, and provide content from third parties.
By using our site, you acknowledge that you have read and understand our Privacy Policy
and Terms of Use.